Unless you are running very hot loads you should get 5000+ out of a 308w hunting barrel, maybe even 10k.
So I'd give it a hard/long clean with a carbon cleaner only to start with. Im of the view that copper helps and not hinders so I dont aim to remove copper. Few ppl agree with me on that, cleaning the barrel til spotless of copper but there you go. I also dont excessively clean, if the first shot is a fouling shot and can vary from the rest that should be telling you something IMHO ie too clean = bad.
You can also get an upper cylinder (car engine) de-carbonising oil from repco ($15?). You could try soaking the barrel in that overnight (even for a week) to soften the carbon, clean after soaking, repeat for some time.
I'd suggest a good quality barrel from a known maker, unknown barrels have been known to fail and injure and a first rate barrel can improve the accuracy of a gun.
regards
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